The role of the microbial loop in benthic communities - combining food web theory and ecological stoichiometry

• Applicant: Professor Dr. Helmut Hillebrand
• Subject Area: Ecology and Biodiversity of Animals and Ecosystems, Organismic Interactions
• Term: from 2004 to 2009
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 5445629

Periphyton communities are often envisioned as primarily autotrophic communities controlled by nutrient and light supply as well as grazer presence. Recent evidence suggests a pivotal, yet underexplored role of the heterotrophic components of periphyton, which comprise bacteria, flagellates, ciliates and meiofauna. Here, we experimentally address the importance of protists for the regeneration of nutrients and thus the production of benthic microalgae. We put a special emphasis on ecological stoichiometry, analysing the flexibility of nutrient content (C:N:P ratio) of protozoan consumers as well as their consequences for the supply rates and ratios to the primary producers. The experiments will cross-classify periphyton communities of different complexity with different conditions of light, nutrient and dissolved organic matter supply. The results will allow 1) describing the functioning of periphyton communities, which represent the most important primary producers in many shallow aquatic habitats, 2) addressing the importance of a microbial loop in the benthos, and 3) extending the concept of ecological stoichiometry to a heterotrophic assemblage.

• DFG Programme: Research Grants